1. Field of the Invention
The present invention relates to a vehicle air bag system that expands at the time of a vehicle collision to protect an occupant.
2. Description of Related Art
Conventionally, an occupant protection device (or referred to an air bag device) is disclosed, in which an air bag is disposed in a folded state at an upper portion of a door opening of a vehicle. The occupant protection device expands the air bag vertically downward by gas injection from an inflator to protect an occupant when an impact is applied onto the vehicle.
For example, Japanese Patent Publication No. 3113977 describes a side air bag device which is disposed extendedly between a front pillar and a roof side rail at peripheries of doors or windows. In the air bag device, a twist determination means is provided around an air bag housed in a folded state, so as to easily confirm the installation state of the air bag.
Further, Japanese Patent Publication No. 3894482 describes an air bag body module in which an air bag is formed in a folded state. Here, a marking for determining whether the air bag is twisted or not is provided with the air bag body module. In addition, another marking for determining whether the air bag is twisted or not is provided with a cover member that locally covers the air bag body module in a longitudinal direction thereof.
However, when an air bag is folded to be elongated, the air bag has a long and narrow shape and is liable to be bent. Accordingly, it is difficult to manage quality of the air bag, particularly prior to an installation of the air bag on a vehicle body. For that reason, the folded air bag in a whole length is housed in a cover made of resin so as to facilitate handling of the air bag.
An inflator, which inflates and expands an air bag vertically downward, is generally inserted into an introduction part having a cylinder-like shape formed protruding from an upper portion of the air bag.
However, there is a case that the introduction part is housed in a twisted state because the introduction part formed protruding from the upper portion of the air bag is liable to be twisted, when the folded air bag is housed in the cover in a state that the inflator is inserted into the introduction part. Further, there is also a case that the introduction part is twisted by being vibrated, when the air bag device is transported while the air bag is housed (or modularized) in the cover.
When the introduction part is twisted, the air bag does not expand smoothly since gas from the inflator is not injected smoothly. Hereby, detachment of the introduction part from the inflator can be occurred. However, it is difficult to confirm the state of the introduction part since the upper portion of the air bag including the introduction part is covered with the cover.